1. Field of the Invention
The present invention relates to housing used in animal husbandry, and particularly to housing adapted for confining small warm-blooded caged animals such as poultry.
2. Prior Art
The structures shown in the U.S. patents discussed briefly below are representative of prior attempts to provide an optimum environment for animal husbandry:
Burgert U.S. Pat. No. 323,782, issued Aug. 4, 1885, discloses a square chicken house having a central top air inlet-outlet and tiers of nesting boards mounted on inclined partitions.
Scott U.S. Pat. No. Re 12,513, reissued July 24, 1906, discloses vertically-spaced tiers of cages mounted at opposite sides of a hollow vertical support.
Cornell U.S. Pat. No. 2,257,734, issued Oct. 7, 1941, discloses a husbandry system in which tiers of cages are moved in a path past feeding, watering and cleaning stations, for example.
Corey U.S. Pat. No. 2,335,173, issued Nov. 23, 1943, discloses a complicated ventilation system for a poultry house having opposing tiers of cages.
Bayer U.S. Pat. No. 3,062,184, issued Nov. 6, 1962, discloses a system for drying manure which has fallen from cages.
Fleshman U.S. Pat. No. 3,994,260, issued Nov. 30, 1976, discloses cages which can be hung from upright columns to form vertically spaced tiers.
Sutton, Jr. U.S. Pat. No. 4,428,278, issued Jan. 31, 1984, discloses mechanism for emergency ventilation of a poultry house.
Truhan U.S. Pat. No. 4,151,811, issued May 1, 1979, discloses a poultry house having a plurality of rooms and mechanism for progressively moving the poultry sequentially through the different rooms.
In general, known husbandry housing for warm-blooded animals has one or more inlets for cool fresh air and one or more outlets for hot stale air. The body heat of the animals contributes to heating the air inside the housing so that, to maintain a given temperature, the ventilation rate is substantially higher in hot weather than in cold weather. A problem with the known housing is that animals near the inlets and animals near the direct airflow path from an inlet to an outlet are exposed to much cooler temperatures than those distant from the inlets and a direct airflow path. This problem is particularly severe in cold weather when the difference in temperature between the cool fresh air and the desired inside temperature is high and the ventilation rate is low.
In addition, in known housings the airflow is interfered with by the interior fixtures and gravity, particularly when the ventilation rate is low, resulting in air stagnation in local areas within the housing. Even if ventilation is positively induced by fans, there can be local microenvironments, some cooled with too much outside air and some hot with dusty air loaded with gases from the animal droppings. These local microenvironments interfere with efficiency of the housing. For example, in the case of a hen house for egg production, productivity of the hens may be reduced.
One known system tries to lessen these problems by locating all of the exhaust openings in one end wall and all of the inlet openings in the opposite end wall. This system lessens the stagnation problem when high ventilation rates are maintained during hot weather, but the temperature of the air in the housing can be much higher at the exhaust end of the room than at the inlet end of the room.
Another known system has inlet vents along the top margins of the sidewalls and exhaust openings in the floor leading to a basement. Air is drawn down through the animal-confining cages to the basement from which it is exhausted to the exterior of the housing. This system can provide a reasonably uniform environment with positive flow through the cages during hot weather but is subject to creation of microenvironments and undesirable stratification during cold weather.